A construction machine including an automatic stop function for automatically stopping an engine when predetermined automatic stop conditions (for example, a gate lever for opening and closing a gateway to a cabin is opened and an operating lever for operating a work actuator is in non-operation) are met has been disclosed in Japanese Patent Laid-Open Nos. 2000-96627 and 2001-41069.
Further, a technique in which when fixed conditions are met (for example, an operating lever for operating a work actuator is not continuously operated for a fixed period) a speed of an engine is automatically reduced to save fuel or the like, so called an automatic deceleration (automatic speed reduction) function is performed, has been generally known.
In a case where the above-mentioned automatic deceleration function is combined with the above-mentioned automatic stop function so that effectiveness/ineffectiveness of both functions can be selected, when automatic stop conditions are met while ineffectiveness of the automatic deceleration function is selected using the automatic stop function, a situation in which the only automatic stop function serves so that an engine is stopped while keeping high engine speed, is generated. Accordingly, the engine and other devices cannot be protected.
It is an object of the present invention to provide an engine control device for a construction machine, which can reliably protect an engine and other devices even in a state where the ineffectiveness of the automatic deceleration function is selected.